coronavirus

15 Settembre 2020 | giochi della chimica 2012 fase nazionale classi A-B | di misefari | 0 Commenti
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Coronavirus: novel coronavirus (COVID-19) infection
TERMINOLOGY
CLINICAL CLARIFICATION
COVID-19 (coronavirus disease 2019) is a respiratory tract infection with a newly recognized coronavirus, SARS-CoV-2,
thought to have originated as a zoonotic virus that has mutated or otherwise adapted in ways that allow human
pathogenicity

○ Disease was provisionally called 2019-nCoV infection at start of outbreak (2019 novel coronavirus infection)
Outbreak began in China but has since spread globally; it was officially declared by WHO to be a pandemic 1
on March 11,
2020

Illness ranges in severity from asymptomatic or mild to severe; a significant proportion of patients with clinically evident
infection develop severe disease, which may be complicated by acute respiratory distress syndrome and shock

Mortality rate among diagnosed cases (case fatality rate) is generally about 5% to 6% globally 2, 3 but varies by country;
true overall mortality rate is uncertain, as the total number of cases (including undiagnosed persons with milder illness)
is unknown

Knowledge of this disease is incomplete and evolving; moreover, coronaviruses are known to mutate and recombine
often, presenting an ongoing challenge to our understanding and to clinical management

CLASSIFICATION
Pathogen is a betacoronavirus, 4
similar to the agents of SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome)

Classified as a member of the species Severe acute respiratory syndrome–related coronavirus 5, 6 ○
Designated as SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2); earlier provisional name was 2019-
nCoV5, 6

DIAGNOSIS
CLINICAL PRESENTATION
• History
In symptomatic patients, illness may evolve over the course of a week or longer, beginning with mild symptoms that
progress (in some cases) to the point of respiratory distress and shock 7

Most common complaints are fever (more than 80%) and cough, which may or may not be productive 8, 7 ○
Myalgia and fatigue are common; fatigue may be profound7 ○
Alteration in smell and/or taste is increasingly reported, often as an early symptom, and is highly suggestive 9 ○
Patients with moderate to severe disease often complain of dyspnea; 7
however, it has been recognized that many
patients with severe hypoxemia due to COVID-19 do not perceive dyspnea 10

Hemoptysis has been reported in a small percentage of patients 7 ○
Pleuritic chest pain has been reported11 ○
○ Upper respiratory tract symptoms (eg, rhinorrhea, sneezing, sore throat) may be present
Headache and gastrointestinal symptoms (eg, nausea, vomiting, diarrhea) are uncommon but may occur 7 ○
○ Patients may or may not report close contact with an infected person
• Physical examination
Reported case series have not fully detailed physical findings, but clinicians should be particularly attuned to
pulmonary and hemodynamic indicators of severe disease

– Patients with severe disease may appear quite ill, with tachypnea and labored respirations
Patients in apparent distress require immediate assessment of airway, breathing, and circulation (eg, pulses, blood
pressure)

Clinicians should be aware of the COVID-19–related phenomenon of silent (or “happy”) hypoxemia: absence of signs
of respiratory distress may be misleading

Oxygenation should be assessed promptly by peripheral saturation (eg, pulse oximetry) 12 –
Fever is typical, often exceeding 39 °C. Patients in the extremes of age or with immunodeficiency may not develop
fever 7

Conjunctival secretions, injection, and chemosis have been reported13 ○
A variety of skin changes have been described, including erythematous
rashes, 14 purpura, 15 petechiae, 16 and vesicles; 17 acral lesions 18, 19, 20 resembling chilblains or Janeway lesions have been
seen, particularly in young patients 21

○ Hypotension, tachycardia, and cool/clammy extremities suggest shock
In children, hypotension plus 2 or more of the following criteria: 12 –
□ Altered mental status
Tachycardia (heart rate more than 160 beats per minute in infants or 150 in older children) or bradycardia (heart
rate less than 90 in infants or 70 in older children)

Published February 5, 2020; Updated July 28, 2020
Copyright © 2020 Elsevier
Coronavirus: novel coronavirus (COVID-19) infection
□ Prolonged capillary refill (more than 2 seconds) or warm vasodilation and bounding pulses
□ Tachypnea
□ Mottled skin, petechiae, or purpura
□ Oliguria
□ Hyperthermia or hypothermia
CAUSES AND RISK FACTORS
• Causes
○ Infection due to SARS-CoV-2 (2019 novel coronavirus)
Person-to-person transmission has been documented11 and is presumed to occur by close contact, 22 probably via
respiratory droplets 23

Viral shedding appears to peak 24 to 48 hours before symptom onset, 24 raising the likelihood of presymptomatic
transmission. Several case and cluster reports from various countries 25, 26, 27 indicating asymptomatic and
presymptomatic transmission have been reported

Additional means of transmission are possible but not established (eg, contact with infected environmental surfaces,
fomites, fecal-oral route)

• Risk factors and/or associations
○ Age
Most reported cases are in adults of middle age or older, 7, 8 but pediatric infections in adolescents and children11,
28 also occur

Risk of severe disease increases with age; in the United States, 94% of deaths occur in people older than 50 years.
Percentage of total mortality by age group: 29 30

□ 0 to 49 years: 5.1%
□ 50 to 64 years: 15.3%
□ 65 to 74 years: 21%
□ 75 to 84 years: 26.4%
□ 85 years or older: 32.1%
○ Sex
Overall, where sex or gender data are available, it appears that females are more often affected, but disease is more
severe in males 29, 31

○ Other risk factors/associations
Various underlying medical conditions have been associated with increased risk for severe disease, especially if they
are not well controlled: 32

□ Chronic kidney disease
□ Chronic obstructive pulmonary disease
□ Immunosuppression because of previous solid organ transplant
□ Malignancy
□ Obesity (BMI of 30 or higher)
□ Serious cardiac conditions (eg, heart failure, coronary artery disease, cardiomyopathy)
□ Sickle cell disease
□ Diabetes type 2
Conditions which may be associated with higher risk for severe disease: 32 –
□ Asthma (moderate to severe)
□ Cerebrovascular disease
□ Cystic fibrosis
□ Hypertension
Immunodeficiency from various other causes (eg, bone marrow or hematopoietic stem cell transplant, primary
immunodeficiencies, HIV disease, chronic treatment with corticosteroids or other agents with
immunosuppressive effects)

□ Neurologic dysfunction
□ Chronic liver disease
□ Pregnancy
□ Pulmonary fibrosis
□ Smoking
□ Thalassemia
□ Diabetes type 1
Children with medically complex conditions (eg, neurologic, metabolic, genetic, cardiac) are also at higher risk for severe disease 32

Published February 5, 2020; Updated

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